Steven Peet has been handed a life sentence for the murder of his partner and her two children in 2016.
Peet received the mandatory sentence for the murders of Adeline Wilson-Rigney, her daughter Amber Rose (6) and son Korey Lee Mitchell (5), and will be in jail for at least 30 years.
The bodies of the woman and children were found on a Hillier property in May 2016, with the court hearing previously that the victims had been strangled with cable ties.
Supreme Court Justice Malcolm Blue labelled the crimes as a 'senseless act'.
"It is obviously very difficult to comprehend how anyone could kill a six-year-old girl and a five-year-old boy in the manner that you did," Justice Blue said.
Peet pleaded guilty to the murder of Ms Wilson-Rigney in August but denied murdering the children, claiming he was in a state of mental disassociation at the time.
He changed his plea in January, saying that he committed all three murders.